Abstract: A masked monopolar sifting filter implemented by multiplying an input signal by a series of shifted nonuniform mask signals and selecting the minimum signal sample value from each resultant product. The intermediate signal thus produced is then again multiplied by the shifted mask signals and the maximum signal sample value from each product chosen to produce a filtered output signal. The filters are particularly useful for edge enhancing features of selected sizes in an image signal.

Abstract: An insect swatter having flexible, parallel, non-overlapping, substantially contiguous tines allowing swatting of insects on regular or irregular surfaces, said tines being arranged to provide a substantially planar surface for striking insects by minimizing the force applied thereto so as to reduce lateral expulsion of insect bodily fluids.

Abstract: A Compound echo-ultrasound imaging system in which the intensity of pixels in an image is a nonlinear function of the amplitude and frequency of echo signals. The dynamic range of a synchronous FM detector in the system is increased by effectively filtering from the echo signals all instantaneous frequencies which would produce intensity levels greater than a corresponding signal of equal amplitude at the carrier frequency of the ultrasound pulses. Filtering may be effectively accomplished by setting the Corner Frequency of the synchronous detector to the carrier frequency of the transmitted pulses.

Abstract: An improved ballast circuit for one or more electric discharge lamps includes a nonlinear variable capacitor connected in series with an iron core inductor and the lamps across the terminals of a source of alternating current. The nonlinear capacitor preferably exhibits a voltage and/or current dependent capacitance characteristic. The use of the nonlinear capacitor improves the crest factor of the lamp current waveform thereby increasing the operating efficiency of the ballast circuit and reducing the size and cost of the iron core inductor.